Carbon Steel Pipe Dimensions & Schedule Chart

Carbon steel pipe is the preferred choice in many applications due to its robustness, corrosion resistance and weldability.

However, to ensure the consistency, compliance, and reliability of carbon steel pipe across different projects, we need to rely on carbon steel pipe dimensional details.

How to correctly express the size of carbon steel pipe?

For your better understanding, we interpret it from the following aspects:

  • Important Parameters for Pipe Dimensions
  • Carbon steel pipe size chart
  • Different Standards for Carbon Steel pipe and Stainless Steel Pipe
  • Dimensions (ASME B36.10M and ASME B36.19M)

Important Parameters of Steel Pipe Dimensions

The size of steel pipe is mainly described from several aspects such as outer diameter, wall thickness, Schedule, and Length.

These dimensional parameters usually play a key role in the steel pipe manufacturing and selection process.

Different application areas and industries may require different dimensional parameters, so understanding and describing these aspects of steel pipe is important to ensure the correct steel pipe is selected.

Carbon Steel Pipe Schedule Chart

ASME B36.10M and ASME B36.19M

They are both dimensions and dimension standards used to regulate steel pipes. The main difference lies in the applicable steel pipe types and application fields:

ASME B36.10M

  • ASME B36.10M is mainly applicable to welded and seamless carbon steel pipes.
  • Carbon steel pipes typically used in general industrial applications such as water supply systems, conveying liquids or gases, and general structural purposes.
  • ASME B36.10M uses the Schedule system to represent steel pipes with different wall thicknesses, such as Schedule 40, Schedule 80, etc.

ASME B36.19M

  • Specifically for stainless steel and nickel alloy tubes, including welded and seamless tubes.
  • This standard is typically used in applications requiring greater corrosion resistance, such as the chemical industry, oil and gas extraction, and food processing.
  • Unlike ASME B36.10M, B36.19M does not use a scheduling system, but directly provides the actual wall thickness (actual thickness) of the pipe.

In general, ASME B36.10M is suitable for general applications of carbon steel pipes and welded and seamless pipes, while ASME B36.19M is specifically suitable for stainless steel and nickel alloy pipes, especially for applications in highly corrosive environments. Which standard to choose depends on the material required and the field of application.

schedule 40 steel pipe and 80 dimension

Schedule 40 and Schedule 80 are used to describe steel pipe specifications of different wall thicknesses. Check out the difference between Schedule 40 and Schedule 80 Pipe.

Here are common carbon steel pipe sizes for Schedule 40 and Schedule 80 (for reference only):

Schedule 40 Steel Pipe

  • Outside Diameter (OD): Typically between 1/8″ and 24″.
  • Wall Thickness: Typically between 2.77mm (0.109 inches) and 17.48mm (0.688 inches).
  • This type of scheduling is commonly used in general industrial applications such as water supply systems, ventilation ducts, etc.

Schedule 80 Steel Pipe

  • Outside Diameter (OD): Typically between 1/8″ and 24″.
  • Wall Thickness: Usually between 3.73mm (0.147 inches) and 22.23mm (0.875 inches).
  • This type of scheduling is typically used in applications that require higher pressure tolerance, such as high pressure air or steam pipelines.

It should be noted that the above dimensions are for reference only. In a specific project, you need to choose the appropriate schedule and size according to the requirements of the project and the purpose of the pipeline. The detailed dimensions of carbon steel pipes can usually be found in relevant standards or specification sheets provided by suppliers.

What is the Nominal Pipe Size (NPS)?

Nominal pipe size (NPS) refers to the standard size of the pipe and describes its outer diameter. NPS is usually expressed in inches.

It is based on US manufacturing standards. It does not directly show the actual pipe size. But, it is an approximation used to find and pick pipes.

NPS is often used in conjunction with pipe wall thickness to determine the actual size of the pipe. In the petroleum industry, common nominal pipe sizes range from 1/8 inch to 120 inches, with each size having a corresponding actual outer diameter.

The choice of pipeline size is usually affected by factors such as flow rate, pressure, and temperature. These factors affect the liquid or gas in the pipeline.

In some countries and regions, the metric system is used. Instead of NPS, the nominal diameter (DN) standard may be used to express pipe dimensions in millimeters or centimeters.

Despite these differences, NPS remains one of the most commonly used pipe sizing standards globally, especially for projects related to the U.S. or North American markets.

So, pipe size standards in different regions should be considered in international engineering projects. Adjust and convert them as needed.

What is DN (Nominal Diameter)

DN (nominal diameter) is an international standard. It indicates the size of piping components like pipes, valves, and flanges.

DN is usually measured in millimeters. It represents the inner or outer diameter of a pipe or pipe component.

The value of DN represents the standard size of the pipe or pipe component. It does not represent the actual inner diameter or outer diameter, but is used to identify pipe components of different sizes.

Assume a water pipe with an actual outer diameter of 50 mm (5 cm). During standardization, we call it DN50, indicating that its nominal diameter is 50 mm.

How to Choose the Correct Steel Pipe Size?

Nominal Pipe Size (NPS):

As mentioned above, this is the standard pipe size used to describe the diameter of the pipe. It is not the actual diameter but a nominal value used for identification.

Outside Diameter (OD):

This refers to the actual outer diameter of the pipe, measured in inches or millimeters. It is important to specify the OD accurately, as it determines the compatibility with fittings and other components.

Wall Thickness (WT):

This measurement indicates the thickness of the pipe wall, which can be measured in either inches or millimeters. It is crucial for determining the pipe’s strength and pressure rating.

Schedule Number:

The schedule number is a designation used to indicate the wall thickness of a pipe. It is related to the NPS and wall thickness and is expressed as a number (e.g., Schedule 40, Schedule 80).


The pipe’s length is typically specified in feet or meters. It is important to specify the length accurately to ensure it meets the project requirements.

When describing steel pipe dimensions, it’s critical to provide all these parameters accurately. This ensures the correct selection and installation of the pipe for the intended use. If you want to determine the pipe size, please consult the UNIASEN steel pipe experts.